This invention relates to fibre-optics, and is particularly concerned with fibre-optic assemblies of a kind for providing distributed emission of light, and with methods of forming such assemblies.
Fibre-optic assemblies of the above-specified kind are already known from U.S. Pat. No. 4,234,907 in which optical fibres that are woven in the manner of a fabric, are scratched or notched at distributed locations along their lengths such that light transmitted along the fibres radiates from those locations. This distributed-light effect may be utilised, for example, for decorative or safety purposes.
It is one of the objects of the invention to provide an improved form of fibre-optic assembly of said above-specified kind.
According to one aspect of the invention a fibre-optic assembly for providing distributed emission of light comprises a multiplicity of fibre-optic strands retained together, wherein each strand comprises a sheathed bundle of optical fibres with discontinuities in the fibres distributed at spaced locations along the strand.
The use of sheathed bundles of optical fibres as the fibre-optic strands, and accommodating discontinuities in the fibres within the sheathing, enables fine optical fibres to be used and the discontinuities to be provided simply by breaks in the fibres. The structural integrity of the fibre-optic strands is maintained by the strand-sheathing, and the difficult task of notching or scratching individual fibres as taught by U.S. Pat. No. 4,234,907, is avoided. This notching or scratching of the fibre strands tends to weaken the fibres and so it is necessary to use thicker fibres than might otherwise be necessary or desirable; the present invention allows a greater degree of choice of strand thickness in that strand thickness is substantially unaffected by the provision of the discontinuities.
According to a feature of the present invention a fibre-optic assembly for providing distributed emission of light comprises a multiplicity of fibre-optic strands bonded together into a sheet, wherein each strand comprises a sheathed bundle of optical fibres with breaks in the fibres distributed at spaced locations along the strand.
The sheet may have the form of a woven fabric with the fibre-optic strands providing, in whole or in part, the warp and/or the weft. More especially, the fibre-optic strands may provide the warp, and the weft may be provided by filaments of plastics (for example, nylon) or metal. The resulting fabric may be used for decorative and/or safety purposes in the context of upholstery, flooring, curtaining, drapes, wall-coverings and wall-hangings, screening, clothing and lighting generally. It may also be incorporated into furniture, for example, into the tops of tables or into counter-tops or other serving surfaces of bars and restaurants, and may be sculpted into works of art.
The sheathing of the individual bundles, which may be of a plastics material (for example, polyvinyl chloride), may be transparent or translucent and encase or encapsulate the optical fibres of the bundle along substantially the whole of its length. Each bundle may comprise more than 100 optical fibres.
The fibre-optic assembly may be used in combination with means for transmitting light into the fibres of the strands so that light is radiated from the distributed locations where the breaks or other discontinuities exist. More especially, different colours of light may be transmitted into different ones of the strands, and the distribution of colours may be varied as between the different strands periodically to provide a changing multi-coloured visual effect.
In accordance with a further object and aspect of the invention there is provided a method of forming a fibre-optic light-emitting assembly wherein a multiplicity of fibre-optic strands each comprising a sheathed bundle of optical fibres, are bonded together, and fibres of each strand are broken at spaced locations along the length of the strand before, during or after the bonding operation.
The bonding operation may be a weaving operation with the fibre-optic strands providing strands of the warp and/or the weft. More especially, the fibre-optic strands may be woven together as the warp, with filaments of plastics or metal as the weft. The breaking of the fibres may take place pseudo-randomly under stresses exerted on the strands during the weaving operation.